Move deprecation warning outside of include guards (#22)

Author: christophfroehlich

tl_expected/include/tl_expected/expected.hpp

@@ -13,9 +13,6 @@
 // <http://creativecommons.org/publicdomain/zero/1.0/>.
 ///
 
-#ifndef TL_EXPECTED_HPP
-#define TL_EXPECTED_HPP
-
 #ifdef _WIN32
 #pragma message( \
   "tl_expected/expected.hpp is deprecated and will be removed by the ROS 2 Lyrical Luth release. \
@@ -26,6 +23,8 @@
   Use <tl/expected.hpp> from libexpected-dev, or <rcpputils/tl_expected/expected.hpp> if the system header is not available."   // NOLINT
 #endif
 
+#ifndef TL_EXPECTED_HPP
+#define TL_EXPECTED_HPP
 
 #define TL_EXPECTED_VERSION_MAJOR 1
 #define TL_EXPECTED_VERSION_MINOR 2